1. Field of the Invention
This invention relates to an electrostatic capacitance detection device.
2. Description of the Related Art
As a conventional technique, in a touch switch device that adopts an input method of an electrostatic capacitance type, an electrostatic capacitance detection device is known that is capable of realizing reduction of malfunction caused in case that water is poured over a surface of panel so as to form droplets without using particular structures or circuits (e.g., refer to JP-A-2008-112334).
The electrostatic capacitance detection device is configured such that data such as a time from On to Off of the switch, a duration time of ON as pattern data of ON and Off of switch operation are preliminarily stored in the control program. A case that droplets are present on the switch electrode is simulated, and the following judgment is carried out. In case of being switched from ON to OFF, the present timer value is read out and the timer value recorded is deducted therefrom, thereby the time during which ON has been maintained is calculated. In case that the calculation time is not more than 100 msec, the matter judged as ON shall be void. In addition, in case of remaining ON, the present timer value is read out and the timer value recorded is deducted therefrom, thereby the time during which ON continues is calculated. In case that the calculation time is not less than 500 msec, ON condition that continues in the present situation shall be void until being judged as OFF. As mentioned above, the conventional technique, for example, JP-A-2008-112334 discloses that unnecessary ON can be excluded and reduction of malfunction due to adherence of droplets can be realized by judging the length of ON time of each switch electrode and ON of a plurality of switch electrodes in the processing of the control program.